The invention relates to a tape drive device in a recording and reproducing device.
In the case where information is recorded on or reproduced from a magnetic tape in a recording and reproducing device such as a cassette tape recorder, the pinch roller presses the magnetic tape onto the capstan which is rotated at a constant speed so that the magnetic tape is run at a constant speed, and the magnetic head, which is normally retracted, is moved forward to contact the magnetic tape so that information can be recorded or reproduced. Also, the reel motor drives the take-up reel to take up the magnetic tape.
Heretofore, the steps of pressing the pinch roller against the capstan, moving the magnetic head forward and starting the reel motor, are carried out simultaneously in response to a regular speed drive instruction signal. However, since it takes time for the magnetic head to reach the pressing position where the head presses the magnetic tape, the reel motor is started to cause the take-up reel to wind the magnetic tape before the head presses the magnetic tape. As a result, a reproducing start position on the magnetic tape is liable to be displaced from a precisely set position. This is due to the fact that the tape tension is further increased when the head is brought into contact with the magnetic tape under the condition that tension is set up in the magnetic tape by the winding torque of the reel motor. Specificially, the pressing contact of the pinch roller against the capstan is completed before the head is brought into contact with the tape, so that the magnetic tape wound on the supply reel is taken up or pulled by the forward movement of the magnetic head. The reproducing start position on the tape is thus displaced and, in addition, a portion of the magnetic tape which is extended on the side of the supply reel from the magnetic head is slackened. As a result, the back tension on the tape supply side as viewed from the pinch roller and the capstan is considerably decreased, causing the running of the magnetic tape to be unstable.